Protective filters are often used to protect users from intense levels of incident light, such as the glare of a welding arc, for example, and have been incorporated in various eyewear, masks, helmets, or other head gear. Automatic darkening filters generally include control circuitry which causes the filter to change from a light state when not subjected to glare and to a dark state upon exposure to such glare. Passive filters generally include a permanently dark filter that may be moved into and out of a position of use over a user's eyes as desired.
Various mechanisms have been provided for automatically shielding a user from a glare of a welding arc or other tool. For example, automatic darkening filters have been provided which darken in response to activation of a tool. Passive filters have been provided that move a protective filter in response to an input of a user or initiation of a welding tool. For example, U.S. Pat. No. 8,047,664 describes a protective automatic darkening filter (ADF) and an associated tool, such as a welding torch, that are controlled by a corresponding communication unit such that the tool is not activated before the ADF has reached its dark state. GB 2034171 describes a filter movable into alignment with a window before a welding arc can be struck and a mechanism involving a solenoid operated device is incorporated into the helmet to actuate movement of the filter. In order to prevent the striking of an arc until the filter is in place, a switch is incorporated which is only operated when the filter is in position and electrical connections between the switch and an electrical control circuit prevent the flow of arc current to a welding tool until the switch has been closed.